Metallica aren't sure when their next album will be out, but James Hetfield can promise that it will be a diverse collection of songs. In a new interview, the singer suggests that, true to form, fans can expect the unexpected when they finally get around to creating the follow-up to 2008's 'Death Magnetic.'

"I don't know where it's going yet but we've got lots of different sounds, different styles," he told Australia's Triple M. "We're certainly not afraid of jumping into past 'feels.' After 'Death Magnetic' we've stopped running hard and started embracing some of our past. 'Master Of Puppets' was kind of a core reference for 'Death Magnetic.'"

Hetfield said the band hasn't found time to properly craft the new songs because they've been so busy with other projects, such as putting together the Orion Music + More Festival, the 'Metallica Through the Never' 3-D concert film and, most of all, their busy concert schedule.

"Yeah, we're trying to write [new material] but gigs keep popping up that are too exciting to stay home for," he continued. "We have lots of material [we've been] working on from the day 'Death Magnetic' ended all the way up until now.

However, when they do give themselves a proper break, there's plenty of material from which they can choose. Hetfield said he has "700 riffs" stockpiled, of which "at least three I've played 20 times."

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